How do I know it will run on my computer ?The Singularity Trap is PHP/MySQL/Javascript, runs on a server, and is played using a browser.
Windows users can get it bundled with UwAmp to run off a thumb drive as a localhost/LAN server.
Most operating systems - Windows also - can use Xampp as the server for localhost/LAN use.
These are free. Try one out ahead of time. Test your browser using the demos or an open play copy.

Can UwAmp run off the main hard drive?Yes. It runs faster/smoother on the main hard drive. Flash thumbs can be slow sometimes, especially when creating a war.
If a flash thumb drive causes timeouts try a newer thumb or use a USB harddrive or copy to internal drive.

A note says:
for your own use only - still covered by the use license - feel free to tweak as desired. Does this mean the code is in clear text?As clear as spaghetti. I was writing the code and the rules at the same time and never went back and cleaned up the code.
Not compiled or anything.

Why sell the prototype for $1.99 ?Mainly so a production version would have to be worthy of a higher price. The prototype is playable like a travel chess set is playable.
When an economy version exists, it should be available as an option.

Can you really use it on a free web host ?Be wary of free hosts that throw ads or block access based on hits - chat and autoreload cause a hit every 10 seconds from that player.
Free hosts with a bandwidth limit should be fine since chat just reads a short text file and auto reload mostly uses the browser cache.